check your build output: https://dashboard.heroku.com/apps/f0314705-340c-4474-97fb-3f62634f55b5/activity/builds/54abefae-d712-40b2-89a6-186ea04244e2 code example

Example 1: heroku logs

heroku logs --tail

Example 2: heroku logs

# Display all logs live
heroku logs -t -a YOUR_APP_NAME

# Only display stdout of your app
heroku logs -t -s app -a YOUR_APP_NAME